many times when i try to start my laptop - i get ablue screen with the error c000021a . after this a memory dump is taken and laptop shuts down .
This happen 3-4 times , then i get a option of System REpain . I try to restore the system . Sometime even duringsystem restore this blue scrren appears . Once System restore is complete , then i can to get to my desktop.
Is this is software problem or my harddrive is damaged/
This error occurs when a user-mode subsystem, such as WinLogon or the Client Server Run-Time Subsystem (CSRSS), has been fatally compromised and security can no longer be guaranteed. In response, the operating system switches to kernel mode. Microsoft Windows
cannot run without WinLogon or CSRSS. Therefore, this is one of the few cases where the failure of a user-mode service can shut down the system.
Mismatched system files can also cause this error. This can occur if you have restored your hard disk from a backup. Some backup programs might skip restoring system files that they determine are in use.
Resolving the Problem
Running the kernel debugger is not useful in this situation because the actual error occurred in a user-mode process.
Resolving an error in a user-mode device driver, system service, or third-party application: Because bug check 0xC000021A occurs in a user-mode process, the most common culprits are third-party applications. If the error occurred after the installation
of a new or updated device driver, system service, or third-party application, the new software should be removed or disabled. Contact the manufacturer of the software about a possible update.
If the error occurs during system startup, restart your computer, and press F8 at the character-based menu that displays the operating system choices. At the resulting Windows
Advanced Options menu, choose the Last Known Good Configuration option. This option is most effective when only one driver or service is added at a time. If this does not resolve the error, try manually removing the offending
software. If the system partition is formatted with file allocation table (FAT), use an MS-DOS startup disk to gain access to the computer's hard disk. If the system partition is formatted with NTFS file system, you might be able to use Safe Mode to rename
or delete the faulty software. If the faulty software is used as part of the system startup process in Safe Mode, you need to start the computer using the Recovery Console in order to access the file. If a newly installed piece if hardware is suspected, remove
it to see if this resolves the issue.
Try running the Emergency Recovery Disk (ERD) and allow the system to repair any errors that it detects.
Resolving a mismatched system file problem: If you have recently restored your hard disk from a backup, check if there is an updated version of the Backup/Restore program available from the manufacturer. Make sure the latest Windows Service Pack
This is my generic bluescreen troubleshooter - you can try Safe Mode as suggested in the article
above - repeatedly tap F8 as you boot. Vista disks are probably needed - if you do not have to try
repair you can borrow a friends as they are not copy protected. Also you can buy the physical disks
from the system maker cheap as you already own Windows (you will need these to reinstall if
required). You can also make repair disks on another computer.
Here are some methods to possibly fix the blue screen issue. If you could give the Blue Screen info
that would help. Such as the BCC and the other 4 entries on the lower left. And any other error
information such as STOP codes and info such as IRQL_NOT_LESS_OR_EQUAL or PAGE_FAULT_IN_NONPAGED_AREA and similar messages.